Andersson had said she would seek an agreement involving the Social Democrats, Left Party, Centre Party and Greens.
Sweden’s parliamentary speaker has formally asked Social Democrat leader Magdalena Andersson to try to form a government after her centre-left alliance won a narrow majority in Sunday’s election.
In a post on Instagram, Andersson said she had accepted the task and that she wanted to "lead a government that realises the new direction that the Swedish people have voted for -- a direction that moves Sweden forward and keeps our country united,"
Andersson has 28 days to assemble her cabinet and report back to the parliamentary speaker, Andreas Norlen. Earlier, Norlen held consultations with party leaders over coffee and a pound cake he baked himself, before announcing his decision to give the Social Democrats leader the go-ahead.
She faces an uphill battle, with many tricky negotiations in the days ahead, with key differences between the four parties in the bloc - the Social Democrats, the Left Party, the Green Party and the Centre Party. In particular, the Left Party has said it would only give its support if it had ministers in the government, an idea the Centre Party has been staunchly opposed to.
If they can find an agreement, it would see Andersson take over as prime minister in the coming weeks, after PM Ulf Kristersson resigned in the wake of the election. Andersson previously served as Sweden’s first female prime minister from 2021 to 2022.
Her centre-left alliance holds a three seat majority in Sweden's 349-seat parliament.
Resigning on Thursday, outgoing prime minister Kristersson called for "constructive openness" across parties to move forward.
"Discussions will need to be held with all parties to find ways around these deadlocks and create the conditions for a stable and effective government," he wrote.